(1) Field of the Invention
The present invention relates to the field of computer graphics. In particular, the present invention relates to a system and a method for detecting human faces in an existing color graphics image.
(2) Description of Related Art
An automatic face recognition system should have the ability to identify one or more persons in a scene, starting from still or video images of the scene. A complete solution of the problem involves segmentation of faces from cluttered scenes, extraction of features from the face region, identification and matching. The first step in this process is face detection. The goal of face detection is to determine whether there is one or more human faces in the image, and, if present, return its location and spatial extent for further processing.
Most of the existing face detection systems use window-based or pixel-based operation to detect faces. In a window-based system, a small window is moved over all portions of an image to determine whether a face exists in each window based on distance metrics. Common problems with window-based approaches are that they cannot detect faces of different orientations or view angles, and that they are computationally expensive.
In representative pixel-based analyses, color segmentation is used as the first step. This assumes that human skin colors fall in a small, known region in color space. Some advantages of using color as feature are speed and invariance to orientation. However, it is difficult to model human skin color for several reasons. One reason is that different cameras produce significantly different color values. Another reason is that human skin color differs from person to person. Finally, skin color distribution shifts with changes in ambient illumination.
Therefore a method for reliably and efficiently detecting human faces within a graphical image is at issue in face recognition systems.